Cigarette paper



United States Patent 3,404,687 CIGARETTE PAPER James C. Rickards, Brevard, and William F. Owens, Jr.,

Pisgah Forest, N.C., assignors to Olin Mathieson Chemical Corporation, a corporation of Virginia No Drawing. Filed Dec. 23, 1966, Ser. No. 604,178 1 Claim. (Cl. 131-15) ABSTRACT OF THE DISCLOSURE This invention provides improved cigarette paper of high porosity to serve as Wrapper for a cigarette tobacco column, which effects a significantly greater reduction of the vapor phase constituents of cigarette smoke than of the particulate constituents. Very high porosity is imparted to the paper by the provision of perforations having length and width dimensions between about 0.001 to 0.015 inch, the size and number being such as to impart to the paper an absolute Greiner porosity index value in the unprecedented low range of about 1 to 3. The perforations are symmetrically arranged with respect to the length and width of the paper, and preferably are arranged in the form of two or three longitudinal rows. The use of the improved cigarette paper of this invention results in cigarettes which yield smoke of reduced content both of vapor phase and particulate constituents, with selective reduction of the vapor phase constituents.

This invention relates to improved paper wrappers for cigarettes and like smoking devices and, more particularly, to improved cigarette paper which is provided with .a plurality of perforations, preferably aligned in rows, said perforations being symmetrically spaced with respect to the length and width of the said paper. The arrangement of the perforations is such that when a cigarette tobacco 3,404,687 Patented Oct. 8, 1968 and in U.S. Patent 3,046,994 issued on July 31, 1962.

On the basis of comparative smoking tests of cigarettes provided with wrappers having a Greiner porosity index of about 10 (absolute value of about .6) attained by a variety of methods, the conclusion stated in the latter disclosure was that essentially the same reduction in particulate content and in contents of gaseous components were found (US. 3,046,994 col. 6, lines 48-68).

It has now been discovered that a selectivereduction of vapor phase constituents in cigarette smoke can be effected by the provision of paper wrappers having much higher porosities, in the range of absolute Greiner porosity index values of about 1 to 3, wherein the porosity is imparted to the wrapper through the provision of symmetrically distributed spaced perforations having length and width dimensions of 0.001 to 0.015 inch. Preferably, such perforations are provided as two or three longitudinal rows, both the perforations and the rows being equally spaced from the adjacent ones in the assembled cigarette. The use of such paper wrappers provides a substantially greater reduction of vapor phase constituents of the cigarette smoke than of the particulate matter, the ratio of percentage reductions generally being about 1.5, and within the range of 1.1 to 2. In other words, cigarette papers perforated in accordance with this invention display a selective reduction of vapor phase constituents of cigarette smoke.

Such selectivity has now been shown to occur uniquely within a range of porosities corresponding to the relatively narrow range of absolute Greiner porosity index values of about 1 to 3, representing porosities much greater than any heretofore proposed as suitable for cigarette wrappers. With respect to such porous wrappers of the prior art,

to Milton 0. Schur displaying a maximum porosity corresponding to a Greiner porosity index value of about 10 (absolute value of 6) or some lower porosity corresponding to a higher index value, the general belief, as supported by the available data, has been that such wrappers effected a reduction in column has been enclosed in a wrapper formed of the concentration of all smoke constituents equally at a given said paper,-the perforations are distributed symmetrically porosity index value. For such wrappers, the selectivity with respect to the length and circumference of the cigratio is 1, this ratio being defined as the quotient of the arette. l V I percentage reduction of vapor phase constituents of the The spaced perforations provided in the paper have smoke divided by the percentage reduction of the parlength and width dimensions between about 0.001 to 0.015 r ticulate constituents. inch, the size and number being so coordinated as to im- The accomplishment of the selective reduction of vapor part an absolute Greiner porosity index value, as herephase constituents of cigarette smoke in accordance with inafter defined, within the range of about 1 to 3. Prefthis invention requires the provision of a porous cigarette erably, the perforations are provided in longitudinal alignpaper characterized by an absolute Greiner porosity index ment, desirably in two or three rows. r value of about 1 to 3, with said porosity being imparted As will be apparent from the following detail descripby symmetrically arranged macroscopic perforations. Such tion and illustrative embodiments, the provision of cigaselective reduction is not attained with the use of paper rette paper wrappers as above defined in accordance with characterized by the stated range of porosity index values, this invention surprisingly enables the attainment of sigwherein the porosity is imparted by other means, for exnificant advantages, V p ample by the provision of sufficient microscopic or sub- Many prior proposals have been made for the use of miCIOSCOPiC Openingsporous cigarette wrapper paper, particularly f paper The above conclusions were based on the results of which has been rendered porous by a perforating treatcomparative experiments of smoking tests as summarized ment, the purpose being to attenuate and cool the smoke. n T bl I and II, characterizing, respectively, the ad- Typical examples were discussed and referred to i the vantageous performance in accordance with this invention article The Design of Low Yield Cigarettes by Schur as contrasted with the confirmation of what might have and Rickards, Tobacco Science, vol. 4, pp. 69-77 (1960) been expected from the prior art.

TABLE I Abs. Greiner Particulate phase Vapor Phase, Cigarette paper porosity Av. Percent Selectivity (sec/50 n11.) Yield Percent Reduction ratio (mg./cig.) Reduction TABLE II Abs. Greiner Particulate phase Vapor Phase, Cigarette paper porosity Av. Percent Selectivity (sec/50 ml.) Yield Percent Reduction ratio (mg./cig.) Reduction Control 19. 1 32. 1 a lnherently porous. 1. 16. 4 48. 8 40. 6 0. 83 1. 5 17. 8 44. 6 39. 8 0. 90 2. 0 17. 8 44. 6 37. 7 0. 85 3. 1 21.4 33. 3 34. 7 1.05 4.1 25. 2 21. 5 18. 5 0. 86 Microscopic perforations 0. 8 14. 7 54. 2 52. 9 0.98 g do 1. 5 20. 4 36.3 31. 6 0.87 2.0 21.3 33. G 32. 3 0. 96 2. 8 22. 4 30. 2 24. 3 0.80 3. 8 22. 7 20. 2 15. 4 0. 53

The above results show that the greatest selective reduction of vapor phase constituents was effected with the use of macroscopically perforated paper listed in Table I, in the range of 1 to 3 seconds absolute Greiner porosity index. No such selectivity was shown in the same range of porosities with the papers listed in Table II.

The test cigarettes of these two tables were prepared by wrapping the tobacco column of the same popular commercial brand of cigarette in wrappers of the same paper, which differed only as indicated with respect to the porosity value and the manner of imparting porosity.

In Examples 1 to 6 of Table I, the macroscopic perforations were produced by means of apparatus as shown in US. Patent 2,699,208 issued Jan. 11, 1955, to Milton 0. Schur to provide two longitudinal rows of perforations, symmetrically spaced apart so that in the wrapped cigarette the rows of perforations are equally spaced from each other. In Examples 1 and 2, there were 30 perforations per inch along each row, produced by rectangular perforating teeth which were initially 0.010 inch in length and 0.001 inch in width. The lower porosity of Example 2 could be produced by the use of lower perforating pressures or of somewhat worn perforating rolls. In Examples 3 and 4, there were 16 perforations per inch along each row, produced by perforating teeth which were initially 0.005 inch by 0.005 inch. In Examples 5 and 6, there were 8 perforations per inch along each row, produced by rectangular perforating teeth which were initially 0.010 inch in length and 0.0025 inch in width. The resulting perforations may be characterized as macroscopic in that they are visible without magnification at normal reading distances.

In contrast, the papers listed in Table II were rendered porous by the production of microscopic openings, through control of the papermaking process, particularly with respect to the extent of beating, in samples a to e and mechanically in samples 1 to j, which were prepared which were prepared as described in U.S. Patent 3,179,- 025, issued Apr. 20, 1965, to Milton 0. Schur. For example, sample it, displaying an absolute Greiner porosity index value of 2.0, was found to contain approximately 75 perforations per square centimeter averaging about 60 microns in diameter.

The porosity index values were measured with the use of a Greiner porosity tester, an instrument long used in the paper industry. The measurement is of the time in seconds for 50 ml. of air to be drawn through a test area of paper one inch in diameter under the influence of a varying suction head corresponding to a column of water averaging about 4 /2 inches in height. The readings have been corrected to absolute values by deducting the time, close to 4 seconds, required for a blank determination, without any paper sample in the instrument. For increased accuracy, the time measurements were carried out automatically by the use of a light absorbing solution and a photo-electric circuit in the apparatus. It will be seen that the time of flow increases with decreasing porosity of the paper sample, and thus, the lower the value of the measured index the more porous is the paper. In testing, care was taken in placing the sample so that the perforations if any were symmetrically arranged with respect to the center of the orifice.

The smoking tests reported herein were carried out in conventional manner, a 35 ml. puff being taken over a two second interval once per minute. In every case, 47 mm. of each cigarette was smoked, using cigarettes which had been conditioned for at least 48 hours at 72 F. and relative humidity of 63%. The cigarettes were selected by weight to be within :2% of the average weight of the group under test.

Particulate matter was removed from the smoke by means of a Cambridge Absolute Filter and weighed.

The quantitative determination of vapor phase constituents was carried out by gas chromatography, generally as described by Irby and Harlow in Tobacco Science vol. 3, 52-56 (1959). The average reduction corresponds to the average of the reductions determined with respect to the eleven constituents listed in Table III.

The smoke analysis results in Table III were obtained on cigarettes prepared by wrapping the tobacco column of a popular commercial brand of cigarettes (not the same as used in the preceding tables) in a standard cigarette paper. Testing was carried out both with cigarettes having unperforated wrappers and having wrappers performated as in Example 4 above (two lines of 0.005 x 0.005 inch perforations, 16 per inch).

TABLE III Unper- Perfo Percent Selec- Smoke Constituent forated rated reductivlty (mg./eig.) (mg./cig.) tion ratio Particulates 27. 65 21. 20 23. 3 Vapor phase constituents:

Isoprene 0. 75 0. 40 46. 6 2.00 Acetaldehyde 1. 02 0. 58 43. 1 1. Acetone. 0.48 0. 33 31. 2 1. 34 McthanoL 0.24 0. 20 16. 7 0. 72 Methyl furarl 0.051 0. 038 25. 5 1. 10

Methyl ethyl ketone 0. 119 0. 084 29. 4 1. 26 Furan 0. 038 0. 025 34. 2 1. 47 Propionaldehyde- 0 076 0. 043 43. 4 1. 87 crolein 0. 122 0. 065 46. 7 2. [)1 Methyl acetate 016 0. 009 43. 8 1. 88 Isobutyraldehyde... 0 032 0. 021 34. 4 1. 47

Average 35. 9 1. 54

The average selectivity ratio of 1.54, confirms the selective reduction of vapor phase constituents in accordance with the invention. The non-selectivity found with respect to methanol occurs occasionally with respect to one or several constituents and is believed to be characteristic of the particular tobacco blend.

The general applicability to a variety of tobacco blends is illustrtaed in Table IV, wherein the analytical results were obtained with 12 different commercial brands of cigarettes produced by various manufacturers. In each case, the cigarette tobacco column was wrapped in a paper wrapper identical to the others, excepting that the controls were unperforated and the others were perforated. In the perforated wrappers, the openings were provided as in Example 4.

TABLE IV Brand Particulate phase, Vapor phase, Selectivity Percent reduction Percent reduction ratio A 23. 2 Y 35. 9 1. 54 B- 35. 8 30. 3 l. C 27.3 40.9 1. 50 D- 19. 0 36. 6 1. 93 E- 21. 4 42. 8 2. 00 F 25. 9 35. 9 1. 38 G- 23. 3 34. 9 1. 50 H. 15. 8 24. 0 1. 52 I- 41.3 49.1 1.20 J 32.4 34.6 1.07 K- 17. 0 36. 4 2. 14 L 17. 7 28. 9 1. 63

The selective reduction in vapor phase constituents of tobacco smoke, thus accomplished in accordance with this invention, advantageously improves the taste and fiavor. Some of these constituents are known to be acrid, irritating or a least unpleasant and the above-described significant lowering in the concentration thereof is beneficial.

The attainment of such selective reduction by using a wrapper of macroporous paper, in contrast to the absence of any selective decrease when a microporous wrapper is used was a surprising as well as advantageous result. Although a verified explanation is not available, it seems probable that the effectiveness of the macroporous paper wrappers of this invention is based on the entrance of lat eral air jets into the cigarette when it is puffed which impinge upon the burning zone with sufiicient velocity to effect a more complete combustion. Such jets have a far higher velocity than the many streams of air entering through a much greater number of tiny pores in a microporous wrapper.

In support of the obtainrnent of more complete combustion at or near the burning zone, it has been determined that generally, lower carbon monoxide content of the smoke results with the use of macroporous rather than microporous paper wrappers, all characterized by The perforated papers were provided with two longitudinal lines of 0.005 by 0.005 inch openings at a density of sixteen per inch. The determinations of nitrogen oxides as nitrogen dioxide were made essentially according to the Salzman procedure, Analytical Chemistry vol. 16, 272-274 (1947).

In contrast with the above-described selective reduction of nitrogen oxides from the smoke with the use of macroporous cigarette paper as wrapper, comparative tests with microporous paper, having an absolute Greiner porosity index Within the range of 1 to 3 imparted inherently by the paper making process or mechanically, showed the absence of such selective reduction.

A similar contrast in smoking test results was establlshed with respect to nitrogenous compounds in the vapor phase of the smoke, as set forth in Table VI.

TABLE VI an absolute Greiner porosity index in the range of 1 to 3. Furthermore, this is paralleled by a greater percentage reduction in the carbon monoxide content than with respect to carbon dioxide.

It has further been indicated that the macroscopic perforations must be symmetrically arranged, in addition to being suflicient in size and number to impart a porosity in the effective critical range. Departures from symmetry in the arrangement of the perforations tends to decrease significantly the selectivity effect.

It should be emphasized that the selectivity effect is attained within the critical range of paper porosities corresponding to absolute Greiner porosity index values of about 1 to 3, a value of about 2 being preferred. At Greiner porosity index values less than 1 and substantially greater than 3, the selectivity effect decreases or Abs. Greiner Particulate Vapor phase N. cmpds., Selectivity percent reduction phase, percent reduction orosity Cigarette paper p (see/50 ml.)

ratio Microporousd0 vanishes. Also, at values less than 0.5, difiiculties arise in easily lighting the cigarette.

The macroscopic perforations should have a length and width dimensions within the range of 0.001 to 0.015 inch. Larger openings are undesirable as tending to weaken the paper or tending to detract from the appearance,

while smaller openings decrease or eliminate the selectivity effect. The shape of the perforations may be varied as desired, provided that the area of the openings is within the specified macroscopic range. Thus, circular, elliptical, crescent, or partially circular, as well as triangular, rectangular or other polygonal shapes are suitable. When the perforating method and apparatus issued is as shown in US. Patent 2,699,208, the perforations should be square or rectangular. However, other methods of perforation may be employed, for example as set forth in U.S. Patents 3,074,303 or 3,021,732. The provision of two or three lines of regularly spaced perforations is preferred as an eifective product can thus be made readily and efiiciently at high production rates.

The selective reduction of vapor phase constituents in accordance with this invention may be applied advantageously to any type of cigarette, including cigarettes provided with any of the available types of filters. Particular advantages may be derived in filter cigarettes combining macroporous paper wrappers as defined herein with a specialized filter tip adapted to remove certain components from the smoke or to supply flavoring ingredients to the smoke.

What is claimed is:

1. A cigarette paper adapted to serve as wrapper for 25 a tobacco column,

said paper being provided with a plurality of macroscopic perforations aligned longitudinally 'in lines containing about 8 to 30 perforations per inch arranged symmetrically about the center of said paper, said perforations having length and width dimensions between .001 and .015 inch and imparting to said paper an absolute Greiner porosity index of about 1 to 3, p whereby smoke drawn from a cigarette tobacco column wrapped with said paper is attenuated by a plurality of substantially symmetrically disposed jets of air directed inwardly through said column, thereby effecting a significant reduction both .of vapor phase and particulate constituents of said smoke with selective reduction of said vapor phase constituents.

References Cited UNITED STATES PATENTS 3,046,994 7/1962 Schur 131 15 FOREIGN PATENTS 998,557 9/1951 France.

594,627 6/1959 Italy.

683,748 4/1964 Canada.

MELVIN D. REIN, Primary Examiner.

IAl hNl UI'HUI:

Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,404,687 October 8, 1968 James C. R'ickards et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below Column 5, line 53, cancel "which were prepared". Column 4, lines 39 and 40, "performated" should read perforated Columns 5 and 6, TABLE V, sub-heading of the fourth column, "Yield (mg./cig.)" should read Yield (ug./Cig.) Column 6 line 5, "a" should read at line 72, cancel "a".

Signed and sealed this 3rd day of March 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Edward M. Fletcher, Jr.

Attesting Officer 

